1. Field of the Invention
The present invention relates to a conveyance method and apparatus for a processing step which can be used in a conveyance line where processing is carried out, such as a coating line in a manufacturing plant where coating is carried out.
2. Description of the Prior Art
Prior art reference 1 (Japanese Unexamined Patent Publication No. 2-123011) and prior art reference 2 (Japanese Unexamined Patent Publication No. 63-275470) disclose coating devices wherein hangers are provided on movable trolley devices guided by a rail laid to follow a coating line, and vehicle bodies supported on the hangers are caused to descend to be immersed in a processing liquid tank.
In the arrangements described above, when a vehicle body is to be immersed in a processing liquid tank, it is caused to run along a rail which descends obliquely downwards, whereby the vehicle body descends and becomes immersed in the processing liquid. Moreover, in order to raise it from the processing liquid, it is caused to run along a rail which ascends obliquely upwards, whereby the vehicle body is removed from the processing liquid. Moreover, in the prior art reference 2, in order to adjust the angle of the vehicle body, wheels provided in front of and behind the trolley device are guided by a separate rail, and the travel rail and the inclining rail are provided with different angles of inclination, in such a manner that the hanger is inclined to a prescribed angle.
However, with variations in production steps, as is the case with small-volume multiple-model productions and the like, production lines which continuously convey vehicles of a same model are decreasing in number, and different types of vehicle bodies are conveyed successively instead. Furthermore, due to improvements in travel safety and the like, vehicle body shapes have become more complicated over the years. Accompanying such complication of vehicle body shapes, in production lines in which vehicle bodies of different shapes are conveyed, it is of essential importance for achieving satisfactory coating to correctly and simply adjust the angle of the vehicle body upon being introduced into the processing liquid and the angle of the vehicle body upon being removed from the same.
However, in the prior art references 1 and 2, it is not possible to adjust the angle of the vehicle body upon being introduced into the processing liquid or the angle of the vehicle body upon being removed from the same, for each different body shape. Hence there has been a problem in that the coating attitude or angle cannot be controlled for each vehicle model and vehicle body shape.
In view of the foregoing, the present invention has an object to provide a conveyance method and apparatus, which can be constituted inexpensively in a compact fashion, whereby the attitude or angle of a process object can be adjusted readily and freely with respect to a processing liquid, and different types of vehicle bodies can be processed satisfactorily by being immersed in a processing liquid.